Using the Polymarket Data API: Real-Time Prediction Market Data for Developers

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers, researchers, and analysts increasingly rely on prediction market intelligence for decision-making and investigation. PolyGram grants access to the Polymarket platform—the globe's premier prediction market—through comprehensive APIs that let builders harness an unparalleled dataset of market signals and pricing information.

Available Data Endpoints

Gamma API (Market Data)

GET https://gamma-api.polymarket.com/events
  ?limit=100&active=true&order=volume24hr
  Returns: event metadata, current prices, volume, tags

GET https://gamma-api.polymarket.com/events/{slug}
  Returns: full event with all markets, prices, descriptions

GET https://gamma-api.polymarket.com/markets/{conditionId}
  Returns: single market details, current order book price

CLOB API (Order Book)

GET https://clob.polymarket.com/book
  ?token_id={tokenId}
  Returns: full order book depth (bids/asks)

GET https://clob.polymarket.com/prices/history
  ?market={conditionId}&resolution=1h&startTs=1700000000
  Returns: hourly price history

WebSocket: wss://ws-subscriptions-clob.polymarket.com
  Subscribe to real-time price updates

Python Quickstart

import requests

# Get top prediction markets by volume
r = requests.get(
    "https://gamma-api.polymarket.com/events",
    params={"limit": 10, "active": "true", "order": "volume24hr"}
)
for event in r.json():
    market = event["markets"][0] if event.get("markets") else {}
    prices = market.get("outcomePrices", "[0.5,0.5]")
    import json; p = json.loads(prices)
    print(f"{event['title'][:50]}: YES={float(p[0]):.2%}")

Use Cases

Research dashboards: Monitor how prediction probabilities shift in real time across specific outcomes and events
News tools: Identify and highlight markets responding to fresh developments and emerging stories
Aggregators: Benchmark odds and implied probabilities from Polymarket against Kalshi, Metaculus, and other platforms
Alert systems: Trigger notifications whenever a market price breaches predetermined boundaries or volatility thresholds
Academic research: Analyse historical settlement records and forecast performance data for validation studies

FAQ

Is the Polymarket API free to use?: Yes — the Gamma API for market data is complimentary subject to rate restrictions (approximately 100 requests per minute without authentication). Submitting orders on the CLOB requires an active funded account, though querying data remains free of charge.
Is there a Python library for Polymarket?: Multiple community-driven Python packages are available on GitHub. Look for "polymarket-py" to locate the most actively maintained implementations.